1 /* 2 * Copyright (C) 2008 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.launcher3; 18 19 import com.android.launcher3.dragndrop.DragView; 20 21 import android.graphics.PointF; 22 import android.graphics.Rect; 23 24 import com.android.launcher3.accessibility.DragViewStateAnnouncer; 25 26 /** 27 * Interface defining an object that can receive a drag. 28 * 29 */ 30 public interface DropTarget { 31 32 class DragObject { 33 public int x = -1; 34 public int y = -1; 35 36 /** X offset from the upper-left corner of the cell to where we touched. */ 37 public int xOffset = -1; 38 39 /** Y offset from the upper-left corner of the cell to where we touched. */ 40 public int yOffset = -1; 41 42 /** This indicates whether a drag is in final stages, either drop or cancel. It 43 * differentiates onDragExit, since this is called when the drag is ending, above 44 * the current drag target, or when the drag moves off the current drag object. 45 */ 46 public boolean dragComplete = false; 47 48 /** The view that moves around while you drag. */ 49 public DragView dragView = null; 50 51 /** The data associated with the object, after item is dropped. */ 52 public ItemInfo dragInfo = null; 53 54 /** The data associated with the object being dragged */ 55 public ItemInfo originalDragInfo = null; 56 57 /** Where the drag originated */ 58 public DragSource dragSource = null; 59 60 /** The object is part of an accessible drag operation */ 61 public boolean accessibleDrag; 62 63 /** Post drag animation runnable */ 64 public Runnable postAnimationRunnable = null; 65 66 /** Indicates that the drag operation was cancelled */ 67 public boolean cancelled = false; 68 69 /** Defers removing the DragView from the DragLayer until after the drop animation. */ 70 public boolean deferDragViewCleanupPostAnimation = true; 71 72 public DragViewStateAnnouncer stateAnnouncer; 73 74 public DragObject() { 75 } 76 77 /** 78 * This is used to compute the visual center of the dragView. This point is then 79 * used to visualize drop locations and determine where to drop an item. The idea is that 80 * the visual center represents the user's interpretation of where the item is, and hence 81 * is the appropriate point to use when determining drop location. 82 */ 83 public final float[] getVisualCenter(float[] recycle) { 84 final float res[] = (recycle == null) ? new float[2] : recycle; 85 86 // These represent the visual top and left of drag view if a dragRect was provided. 87 // If a dragRect was not provided, then they correspond to the actual view left and 88 // top, as the dragRect is in that case taken to be the entire dragView. 89 // R.dimen.dragViewOffsetY. 90 int left = x - xOffset; 91 int top = y - yOffset; 92 93 // In order to find the visual center, we shift by half the dragRect 94 res[0] = left + dragView.getDragRegion().width() / 2; 95 res[1] = top + dragView.getDragRegion().height() / 2; 96 97 return res; 98 } 99 } 100 101 /** 102 * Used to temporarily disable certain drop targets 103 * 104 * @return boolean specifying whether this drop target is currently enabled 105 */ 106 boolean isDropEnabled(); 107 108 /** 109 * Handle an object being dropped on the DropTarget 110 * 111 * @param source DragSource where the drag started 112 * @param x X coordinate of the drop location 113 * @param y Y coordinate of the drop location 114 * @param xOffset Horizontal offset with the object being dragged where the original 115 * touch happened 116 * @param yOffset Vertical offset with the object being dragged where the original 117 * touch happened 118 * @param dragView The DragView that's being dragged around on screen. 119 * @param dragInfo Data associated with the object being dragged 120 * 121 */ 122 void onDrop(DragObject dragObject); 123 124 void onDragEnter(DragObject dragObject); 125 126 void onDragOver(DragObject dragObject); 127 128 void onDragExit(DragObject dragObject); 129 130 /** 131 * Handle an object being dropped as a result of flinging to delete and will be called in place 132 * of onDrop(). (This is only called on objects that are set as the DragController's 133 * fling-to-delete target. 134 */ 135 void onFlingToDelete(DragObject dragObject, PointF vec); 136 137 /** 138 * Check if a drop action can occur at, or near, the requested location. 139 * This will be called just before onDrop. 140 * 141 * @param source DragSource where the drag started 142 * @param x X coordinate of the drop location 143 * @param y Y coordinate of the drop location 144 * @param xOffset Horizontal offset with the object being dragged where the 145 * original touch happened 146 * @param yOffset Vertical offset with the object being dragged where the 147 * original touch happened 148 * @param dragView The DragView that's being dragged around on screen. 149 * @param dragInfo Data associated with the object being dragged 150 * @return True if the drop will be accepted, false otherwise. 151 */ 152 boolean acceptDrop(DragObject dragObject); 153 154 void prepareAccessibilityDrop(); 155 156 // These methods are implemented in Views 157 void getHitRectRelativeToDragLayer(Rect outRect); 158 } 159
